Variable rotary cutter and make-ready method with knife-change-only capability

Abstract

A variable rotary cutter and method for setting up a knife cylinder of such a cutter that reduces the setup (make-ready) time for the cutter by eliminating the requirement to install, remove, and move knife holders on the knife cylinder. The knife cylinder has a plurality of knife holders circumferentially positioned about the circumference of the knife cylinder. At least some of the knife holders extend the axial length of the knife cylinder and are configured to permit multiple knife blades of different lengths to be mounted therein end-to-end across the entire axial length of the knife cylinder. At least one knife blade can be mounted in at least a first of the knife holders, while knife blades are not mounted in at least a second of the knife holders so that rotation of the knife cylinder against a web material forms incisions spaced apart a first spacing distance in the web material. Thereafter, the knife cylinder can be reconfigured without repositioning any of the knife holders on the knife cylinder, but instead by removing, repositioning, and/or installing knife blades on the knife holders.

1 . A method of readying a knife cylinder for making incisions in web materials that pass between the knife cylinder and an anvil cylinder, the method comprising the steps of: 
 providing the knife cylinder with a plurality of knife holder devices circumferentially positioned about the circumference of the knife cylinder, at least some of the knife holder devices defining knife holders that extend the axial length of the knife cylinder and are configured to permit multiple knife blades of different lengths to be mounted therein end-to-end across the axial length of the knife cylinder in its entirety;    mounting at least one knife blade in at least a first of the knife holders while not mounting any knife blades in at least a second of the knife holders;    rotating the knife cylinder to form incisions spaced apart a first spacing distance in a web material passing between the knife and anvil cylinders; and then    reconfiguring the knife cylinder without repositioning any of the knife holders on the knife cylinder by performing at least one step chosen from the group consisting of repositioning the at least one knife blade on the first knife holder, removing the at least one knife blade from the first knife holder, and mounting at least one knife blade in the second knife holder; and    rotating the knife cylinder to form incisions spaced apart a second spacing distance in a web material passing between the knife and anvil cylinders, wherein the first and second spacing distances are different.    
   
   
       2 . The method according to  claim 1 , wherein the knife and anvil cylinders rotate synchronously but in opposite rotational directions during the rotating steps.  
   
   
       3 . The method according to  claim 1 , wherein the mounting step comprises mounting at least two knife blades in at least the first knife holder.  
   
   
       4 . The method according to  claim 1 , wherein the mounting step further comprises mounting at least one knife blade in at least a third of the knife holders.  
   
   
       5 . The method according to  claim 4 , wherein the knife blades are mounted in the first and third knife holders to perform a bleed cut when rotating the knife cylinder to form the incisions spaced apart the first spacing distance.  
   
   
       6 . The method according to  claim 1 , wherein the reconfiguring step comprises removing the at least one knife blade from the first knife holder but not mounting a knife blade in the second knife holder.  
   
   
       7 . The method according to  claim 1 , wherein the reconfiguring step comprises mounting at least one knife blade in the second knife holder.  
   
   
       8 . The method according to  claim 7 , wherein the reconfiguring step further comprises mounting at least one knife blade in at least a third of the knife holders.  
   
   
       9 . The method according to  claim 8 , wherein the knife blades are mounted in the second and third knife holders to perform a bleed cut when rotating the knife cylinder to form the incisions spaced apart the second spacing distance.  
   
   
       10 . The method according to  claim 1 , wherein the reconfiguring step comprises removing the at least one knife blade from the first knife holder and mounting at least one knife blade in the second knife holder.  
   
   
       11 . The method according to  claim 1 , wherein the reconfiguring step comprises mounting at least two knife blades in at least the second knife holder.  
   
   
       12 . A method of readying a knife cylinder for making incisions in web materials that pass between the knife cylinder and an anvil cylinder, the method comprising the steps of: 
 mounting a plurality of knife holders to the knife cylinder, the knife holders extending the entire axial length of the knife cylinder and being circumferentially positioned about the circumference of the knife cylinder, each of the knife holders being configured to permit multiple knife blades of different lengths to be mounted therein end-to-end across the axial length of the knife cylinder;    mounting at least one knife blade in at least a first of the knife holders while not mounting any knife blades in at least a second of the knife holders so that incisions spaced apart a first spacing distance can be made in a first web material passing between the knife and anvil cylinders; and then    subsequently mounting at least one knife blade in at least the second knife holder so that incisions spaced apart a second spacing distance can be made in a second web material passing between the knife and anvil cylinders without repositioning any of the knife holders on the knife cylinder.    
   
   
       13 . The method according to  claim 12 , further comprising the step of making incisions in the first and second web materials following the mounting step and following the subsequent mounting step by causing the knife and anvil cylinders to rotate synchronously but in opposite rotational directions.  
   
   
       14 . The method according to  claim 12 , wherein the mounting step comprises mounting at least two knife blades in at least the first knife holder.  
   
   
       15 . The method according to  claim 12 , wherein the mounting step further comprises mounting at least one knife blade in at least a third of the knife holders.  
   
   
       16 . The method according to  claim 1 , wherein the subsequent mounting step further comprises removing the at least one knife blade from the first knife holder.  
   
   
       17 . The method according to  claim 2 , wherein at least one of the mounting step and the subsequent mounting step further comprises mounting at least one knife blade in at least a third of the knife holders.  
   
   
       18 . A knife cylinder for making incisions in a web material passing between the knife cylinder and an anvil cylinder adjacent thereto, the knife cylinder comprising: 
 a plurality of knife holder devices mounted to the knife cylinder to define knife holders circumferentially positioned about the circumference of the knife cylinder, the knife holders extending the entire axial length of the knife cylinder and being configured to permit multiple knife blades of different lengths to be mounted therein end-to-end across the axial length of the knife cylinder in its entirety; and    at least one knife blade mounted in at least a first of the knife holders while a knife blade is not mounted in at least a second of the knife holders.    
   
   
       19 . A knife cylinder according to  claim 18 , wherein most of the knife holders do not have a knife blade mounted therein.  
   
   
       20 . A knife cylinder according to  claim 18 , wherein the knife holders substantially fill the entire circumference of the knife cylinder.